We report Magnetospheric Multiscale observations of lower hybrid and whistler waves at the compression region of a foreshock transient. Lower hybrid waves (LHWs) are observed at the boundaries of the compression region and excited by the instability associated with the density gradient. Electron fluxes parallel to the magnetic field exhibit oscillations at the frequency band close to the LHWs. Associated with LHWs, electron plateau-like distributions in the parallel direction are observed during burst intervals. Evidence suggests that the LHWs likely contribute to parallel electron heating through Landau damping. Within the compression region, whistler waves are found driven by the electron perpendicular temperature anisotropy associated with the magnetic field pileup. These two types of plasma waves are intrinsically linked to the expansion of the transient. These results provide insights on the kinetic-scale wave-particle interactions associated with foreshock transients.
展开▼
